JP2006265592A - Wet treatment method for zinc leaching residue - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wet treatment method for zinc leaching residue by which the amount of copper source substance to be added required for reducing the grade of rare metal such as indium in a solid content mainly including copper and arsenic as copper arsenide is easily determined, and an increase in cost can be suppressed as a result. <P>SOLUTION: The wet treatment method for zinc leaching residue is provided with: a leaching step where zinc leaching residue removed as a solid content by leaching roasted ore and subjecting the zinc leaching residue to solid-liquid separation in zinc hydrometallurgy is leached with acid, and is subjected to solid-liquid separation; a first neutralizing step where the leach liquor obtained by the leaching step is neutralized, and is subjected to solid-liquid separation; an arsenic removing step where the neutralized liquid obtained by the first neutralizing step is subjected to arsenic removal, and is subjected to solid-liquid separation; a second neutralizing step where the liquid obtained by the arsenic removing step is neutralized, and is subjected to solid-liquid separation; and an iron removing step where the neutralized liquid obtained by the second neutralizing step is subjected to iron removal, and is subjected to solid-liquid separation. In the above method, when the neutralized liquid obtained by the first neutralizing step is subjected to arsenic removal, zinc dust and copper ion source substance such as copper sulfate are added to the neutralized liquid. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for wet treatment of zinc leaching residue, and in particular, iron is mainly removed from the zinc leaching residue as hematite in order to recover zinc remaining in the zinc leaching residue separated in the zinc leaching step of wet zinc smelting. The present invention relates to a wet processing method for zinc leaching residue that is returned to the zinc leaching step.

  The raw ore of wet zinc smelting usually contains 1 to 12% iron, and forms zinc ferrite corresponding to iron in a roasting furnace. This zinc ferrite is insoluble under normal leaching (roasted ore) leaching conditions, so when zinc is leached in wet zinc smelting, it is removed together with other components other than zinc as zinc leaching residue .

  This zinc leaching residue contains zinc that could not be leached, and various other elements including iron and valuable metals, so in order to recover the zinc remaining in the zinc leaching residue, After removing iron and valuable metals other than zinc and collecting them, the treated liquid is returned to the zinc leaching process of zinc smelting.

  As a method of separating and removing iron in order to recover zinc from such zinc leaching residue (zinc ferrite), it has traditionally been called jarosite process, goethite process and hematite process from the chemical name of the iron residue produced The three processes are in practical use.

Of these three processes, the jarosite process and the goethite process have few examples of effectively recycling the produced iron starch, and in order to use iron starch as a valuable metal instead of waste, The hematite process is considered the most suitable. However, in the conventional hematite process, the amount of impurities in the generated hematite (Fe ₂ O ₃ ) could not be reduced to a satisfactory level.

  Therefore, hematite can be recovered by reducing the amount of impurities in the hematite generated when the zinc leaching residue of wet zinc smelting is processed by the hematite process, and other than iron, such as gold, silver, copper or lead There has been proposed a wet processing method for zinc leaching residue that can effectively separate and recover valuable metals (see, for example, Patent Document 1). In this method, a zinc oxide leaching residue removed by solid liquefaction by leaching sinter with wet zinc smelting is added to an electrolytic tail solution in wet zinc smelting to form a pulp, and then reduced to a reduced atmosphere. Leached and separated into solid and liquid, separated into solids containing lead and silver as main components and leachate containing other components (leaching process), calcium carbonate was added to this leachate, and free sulfuric acid in the leachate was After mixing and solid-liquid separation, it is separated into a solid containing gypsum as a main component and a neutralized liquid containing other components (first neutralization step), and zinc powder is added to this neutralized liquid to obtain a solid-liquid solution. Separated into a liquid containing mainly copper and arsenic as copper arsenide and a liquid containing other components (de-arsenic process). Calcium carbonate is added to the liquid after separating copper arsenide in this de-arsenic process While raising the pH, solid-liquid separation, Separated into a liquid containing other components (second stage neutralization step), the liquid after separating the aluminum in the second stage neutralization step was hydrolyzed while oxidizing iron in the hematite generation temperature region and then solidified After separation and separation into a solid containing iron as hematite and a liquid containing zinc (deironing step), this dearsenic iron solution is returned to the leaching step of zinc smelting.

JP 2002-30355 (paragraph number 0006-0012)

  In the method proposed in Patent Document 1, when the amount of copper ions in the neutralized solution obtained in the first stage neutralization step is too small, copper and arsenic obtained in the dearsenation step are mainly contained as copper arsenide. The quality of rare metals such as indium (In) in the solid content increases, and the recovery rate of rare metals decreases. Conventionally, this copper ion source could be covered by the unavoidable copper source material in the ore, but it may be necessary to add the copper source material due to changes in the composition of the ore in recent years (raw material composition). The copper source material was added before roasting the raw ore of the wet zinc smelting. However, when using raw ores that do not require the addition of a copper source material, the copper source material will be added, and the addition amount of the copper source material cannot be determined. If it is too much, the cost increases.

  Therefore, in view of such a conventional problem, the present invention provides indium (In) in a solid content mainly containing copper and arsenic as copper arsenide obtained in the arsenic removal step of the wet processing method of zinc leaching residue. An object of the present invention is to provide a method for wet treatment of zinc leaching residue, which can easily determine the amount of addition of a copper source material necessary for reducing the quality of rare metal and suppress an increase in cost.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that when neutralizing the neutralized solution obtained in the first stage neutralization step, copper ions are added to the neutralized solution in addition to zinc powder. Necessary to reduce the quality of rare metals such as indium (In) in solids mainly containing copper and arsenic as copper arsenide obtained in the arsenic removal process of the wet processing method of zinc leaching residue by adding source materials It has been found that the amount of copper source material added can be easily determined to suppress an increase in cost, and the present invention has been completed.

  That is, the method of wet treatment of zinc leaching residue according to the present invention is a method of leaching zinc leaching residue removed by solid liquefaction by leaching sinter with wet zinc smelting and solid-liquid separation by leaching with acid. A leaching step, a first stage neutralization step of neutralizing and separating the leachate obtained in the leaching step, and a neutralization solution obtained in the first step neutralization step to remove arsenic and solidify The arsenic removal step for liquid separation, the second-stage neutralization step for neutralizing the liquid obtained in this arsenic removal step and solid-liquid separation, and the neutralization solution obtained in this second-stage neutralization step are removed. In the wet leaching process of zinc leaching residue comprising a deironing step of iron and solid-liquid separation, when the neutralized solution obtained in the first stage neutralization step is dearsenized, And a copper ion source material such as copper sulfate.

  In this zinc leaching residue wet processing method, the amount of the copper ion source material added is the ratio of the Cu concentration to the As concentration in the reaction tank for de-arsenizing the neutralized solution obtained in the first stage neutralization step ( (Cu / As ratio) is preferably determined based on the Cu / As ratio, and the Cu / As ratio is preferably determined to be 1.5 or more. Alternatively, it is preferable that the amount of the copper ion source material added is determined based on the potential in the reaction vessel for removing the neutralized solution obtained in the first stage neutralization step, and this potential is −320 mV or more. It is preferable to be determined, and it is further preferable to be determined to be −300 mV or higher.

  In the wet leaching process for zinc leaching residue, it is preferable that at least one valuable metal selected from the group consisting of gold, silver, copper, iron and lead is separated and recovered from the zinc leaching residue. In the leaching process, electrolytic tail liquor in wet zinc smelting is added to the zinc leaching residue to make a pulp, then leached in a reducing atmosphere and solid-liquid separated, solids containing lead and silver as main components, and other components It is preferable that it is the process of isolate | separating into the leaching liquid containing. In the first stage neutralization step, calcium carbonate is added to the leachate obtained in the leaching step, the free sulfuric acid in the leachate is neutralized and solid-liquid separated, and the solid content mainly composed of gypsum and other components are removed. It is preferable that it is the process of isolate | separating into the liquid to contain. In the arsenic removal process, zinc powder and a copper ion source material are added to the neutralized solution obtained in the first stage neutralization process and separated into solid and liquid, and the solid content mainly containing copper and arsenic as copper arsenide is added. It is preferably a step of separating into a liquid containing components. In the second stage neutralization step, the solution after separation of copper arsenide in the dearsenation step is subjected to solid-liquid separation by increasing the pH while adding calcium carbonate, and contains solids mainly composed of aluminum and other components. The step of separating into liquids is preferred. In the iron removal step, the liquid after the separation of aluminum in the second stage neutralization step is hydrolyzed while oxidizing iron in the hematite generation temperature region, and then solid separated, and the solid content containing iron as hematite and zinc are separated. It is preferable that it is the process of isolate | separating into the liquid to contain. In addition, zinc powder is added to the liquid obtained in the second stage neutralization step and solid-liquid separated between the second stage neutralization step and the iron removal step, and arsenic, cadmium and lead are contained as main components. You may provide the 2nd step | paragraph de-arsenic process isolate | separated into the liquid containing solid content and another component. Further, it is preferable that the amount of copper in the leaching solution obtained in the leaching step is 3 mol or more with respect to 1 mol of arsenic, and this leaching solution is reacted with arsenic in the arsenic removing step to form copper arsenide.

  According to the present invention, the copper source necessary for reducing the quality of rare metals such as indium (In) in the solid content mainly containing copper and arsenic as copper arsenide obtained in the de-arsenic step of the wet processing method of zinc leaching residue An increase in cost can be suppressed by easily determining the amount of substance added.

  Hereinafter, an embodiment of a wet processing method for a zinc leaching residue according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 schematically shows the steps of an embodiment of the wet processing method for zinc leaching residue according to the present invention. As shown in FIG. 1, in the embodiment of the wet processing method of zinc leaching residue according to the present invention, the zinc leaching residue removed by solid liquefaction by leaching the sinter with wet zinc smelting is separated. After the leaching process, the first stage neutralization process, the dearsenation process, the second stage neutralization process and the iron removal process, the dearsenic iron solution is returned to the zinc smelting leaching process for use. Hereinafter, each of these steps will be described.

  First, in wet zinc smelting, the smelted ore obtained by roasting ore is leached and subjected to solid-liquid separation (separated into solid (S) and liquid (L)), and a leachate rich in zinc, Separated into zinc leaching residues as solids containing iron, copper, gold, silver, lead, etc. After subjecting the leachate obtained by this solid-liquid separation to a liquid purification treatment, zinc is recovered by an electrolysis process. The liquid (electrolytic tail liquid) after zinc is recovered by this electrolysis process is used after being returned to the above-described zinc smelting leaching process and liquid cleaning process, and also in the leaching process of zinc leaching residue described later. Supplied and reused.

(1) Leaching step In this leaching step, the zinc leaching residue obtained by the above-described wet zinc smelting is added to the zinc smelting electrolytic tail liquor to form a pulp, and then leached in a reducing atmosphere such as SO _2. Then, it is separated into a solid and a liquid and separated into a solid containing lead and silver as main components and a leachate containing other components. Specifically, the zinc leaching residue obtained by wet zinc smelting is added with the electrolytic tail liquor of the above zinc smelting to obtain a pulp of 150 to 250 g / L. Next, reductive leaching is performed at an SO ₂ partial pressure of 0.15 to 0.25 MPa and a temperature of 80 ° C. or higher, preferably 100 ° C. or higher. This SO ₂ leaching causes the following decoppering reaction.
ZnS + H ₂ SO ₄ = ZnSO ₄ + H ₂ S
2ZnS + 2H ₂ SO ₄ + SO ₂ = 2ZnSO ₄ + 2H ₂ O + 3S
CuSO ₄ + S + SO ₂ + 2H ₂ O = CuS + 2H ₂ SO ₄
CuSO ₄ + H ₂ S = CuS + H ₂ SO ₄

In this leaching step, leaching is performed in a reducing atmosphere such as SO ₂ without adding ZnS or S ⁰ to the zinc leaching residue. By leaching in this manner, the amount of copper in the obtained leachate is set to 3 mol or more with respect to 1 mol of arsenic, and is reacted with arsenic in a subsequent dearsenic process to form copper arsenide (Cu ₃ As). Therefore, it is possible to secure a sufficient concentration of copper. As a result, the arsenic removal in the arsenic removal process proceeds more completely, and the amount of arsenic in the solid material mainly composed of iron oxide recovered in the iron removal process can be further reduced. On the other hand, when the copper containing residue to precipitate the copper in the leaching solution by adding ZnS or S ⁰ to zinc leaching residue in the leaching step, de砒after de砒process becomes difficult, is recovered by removing iron oxidizing step It becomes difficult to reduce the impurity concentration in the solid mainly composed of iron.

  The leachate (L) sent to the next step is 30-40 g / L free sulfuric acid, 60-100 g / L Zn, 30-50 g / L Fe, 2-3 g / L Cu, 5 to 1 g / L As. On the other hand, the solid content (S), which is a starch that is separated and removed, contains hardly soluble salts such as lead, silica, gold, and silver, and is used as a raw material for lead smelting.

(2) First stage neutralization step In this first stage neutralization step, calcium carbonate is added to the leachate obtained in the above leaching step to neutralize the free sulfuric acid in the leachate for solid-liquid separation, and gypsum. Is separated into a liquid containing a solid content mainly composed of and other components. This neutralization step is performed in order to neutralize the leachate after the above leaching step, since it contains free sulfuric acid to the extent that it significantly inhibits the formation of hematite in the subsequent deironing step. The concentration of free sulfuric acid after neutralization is adjusted to 3 to 10 g / L, and gypsum is obtained by solid-liquid separation of the slurry after the reaction. In order to prevent gypsum coloring due to iron precipitation and obtain gypsum that can be sold, it is preferable to neutralize the free sulfuric acid so that the concentration does not become less than 3 g / L.

(3) De-arsenic step In this de-arsenic step, the zinc powder (ZnD (zinc) was added to the neutralization solution obtained in the first-stage neutralization step to -300 mV while measuring with a silver / silver chloride electrode. dust)) to separate into solid and liquid and separate into solid containing mainly copper and arsenic as copper arsenide and liquid containing other components. In this arsenic removal step, arsenic in the liquid is not completely removed. If priority is given to removing arsenic completely, cadmium is also precipitated, making it difficult to recover this cadmium.

  In this way, after mainly removing gypsum in the first stage neutralization step and before the second stage neutralization step, arsenic is removed in the dearsenation step, so that iron oxide recovered in the subsequent deironation step is mainly used. It is possible to prevent a predetermined amount or more of impurities from being included in the solid matter. Thereby, it can utilize as a manufacturing raw material of cement, etc., without making the solid substance which contains iron oxide as a collect | recovered main component into a waste material.

  Also, in this arsenic removal process, the rare metal grade such as indium (In) in the solid content mainly containing copper and arsenic as copper arsenide obtained in this arsenic removal process is reduced to increase the recovery rate of the rare metal. In addition to the zinc powder, a necessary amount of copper sulfate solution is added to the dearsenic reaction tank. In order to determine the amount of copper sulfate added, the relationship between the potential in the dearsenic reaction tank and the Cu / As ratio (ratio of the Cu concentration to the As concentration), the potential in the dearsenic reaction tank and the dearsenic residue The relationship between the indium quality in the dearsenic residue and the Cu / As ratio in the dearsenic reaction tank was investigated by investigating the relationship with the indium quality in the dearsenic. These results are shown in FIGS. As can be seen from FIG. 4, if the Cu / As ratio in the dearsenic reaction tank can be maintained at 1.5 or more, the quality of indium in the dearsenic residue is increased (the amount of indium precipitated in the dearsenic process is increased). ) And the recovery rate of indium recovered in the next step can be increased, and the quality of As in iron oxide (hematite) can be maintained at a low level. Further, as can be seen from FIG. 2, when the Cu / As ratio in the dearsenic reaction tank is maintained at 1.5 or more, the potential control value in the dearsenic reaction tank is −300 mV or more (ideally around −200 mV). As can be seen from FIG. 3, when the potential control value in the dearsenic reaction tank is changed to −300 mV or more, an increase in the quality of indium in the dearsenic residue can be suppressed. From these results, the amount of copper sulfate added was adjusted so that the Cu / As ratio in the dearsenic reaction tank was maintained at 1.5 or higher, or the potential control value in the dearsenic reaction tank was maintained at -300 mV or higher. You can see that it should be decided.

  In addition, as copper sulfate to be added here, precipitated copper or clean copper residue obtained by precipitation of copper using iron scrap in copper and lead smelting is leached with electrolytic tail liquor of wet zinc smelting. Can be manufactured. However, since it is not leached as it is with copper, it is preferable to add a starch slurry containing Mn starch from the zinc electrowinning step to the leaching tank. Manganese is an element necessary for impurity purification and zinc electrowinning, and is repeatedly leached. In this way, copper is leached using manganese within the balance of the quantity of zinc smelting, degrading the quality of indium in the dearsenic residue, and manganese is also leached, so the balance of manganese in the system Can also keep normal.

  By this dearsenation step, the concentration of Cu in the liquid is reduced from 2 g / L to 5 mg / L, and the concentration of As is reduced from 750 mg / L to 15 mg / L. The copper arsenide removed from the liquid is sent to copper smelting. In this copper smelting, a process is generally employed in which only copper is separated from a solution containing copper and arsenic, and then arsenic is immobilized as iron arsenate. Copper arsenide can be easily dissolved in this process because it can be easily dissolved in an oxidizing atmosphere. The copper recovery rate by this process is comparable to the recovery rate by the conventional hematite process with a leaching step or a copper removal step as a subsequent step.

(4) Second stage neutralization process In this second stage neutralization process, the pH is raised to 4 to 4.6 while adding calcium carbonate to the liquid after separation of copper arsenide in the above-mentioned dearsenicization process, and the solid liquid Separated into a liquid containing a solid content mainly composed of aluminum and other components. Aluminum is also removed because it is one of the inhibitors of hematite formation. The reason why the pH is set to 4 to 4.6 is that separation of aluminum is insufficient when the pH is less than 4, and precipitation of Zn and Fe starts when the pH exceeds 4.6.

(5) Deironing step In this deironing step, the liquid after the separation of aluminum in the second stage neutralization step is hydrolyzed while oxidizing iron in the hematite generation temperature region, and then solid separated to obtain iron. It separates into a solid containing hematite and a liquid containing zinc. Specifically, the liquid obtained in the second stage neutralization step is heated to 190 ° C. or higher, which is the temperature at which hematite precipitates in an equilibrium manner, and the O ₂ partial pressure is 0.1 to 0.3 MPa. After reacting in an oxidizing atmosphere, hematite is obtained by filtering under reduced pressure. In the liquid after the reaction, the Zn content is maintained at 60 to 100 g / L, but the Fe content is decreased to 6 g / L or less. The liquid after the iron removal process is sent again to the zinc smelting leaching process and used as a raw material for zinc recovery.

  In addition, you may add a 2nd stage dearsenic process between said 2nd stage neutralization process and iron removal process. In this second-stage dearsenation step, zinc powder is added to the liquid obtained in the second-stage neutralization step for solid-liquid separation, and the solid content containing arsenic, cadmium and lead as main components and other components are included. Separate into liquid. Specifically, sulfuric acid is added to the liquid obtained in the second stage neutralization step to adjust the pH to 3.0 to 3.5, and 2 g / L of zinc powder is added. The pH is adjusted to 3.0 to 3.5 because a large amount of iron is present in the treatment liquid in the second stage de-arsenic process, so that the pH of the liquid obtained in the second stage neutralization process is adjusted. This is because the filterability is significantly inhibited by the production of iron hydroxide. By this second stage dearsenation step, a liquid from which impurities such as arsenic, cadmium and lead are almost completely removed can be sent to the next deironation step. Therefore, the amount of impurities contained in the iron oxide recovered in the next deironing step can be remarkably reduced, and can be effectively used for producing cement.

  In this way, in the second stage dearsenation process after the second stage neutralization process and before the iron removal process, arsenic is almost completely not contained in the solid matter mainly composed of iron oxide recovered in the iron removal process. In addition, the amount of impurities such as cadmium and lead can be reduced.

It is process drawing which shows schematically embodiment of the wet processing method of the zinc leaching residue by this invention. It is a graph which shows the relationship between the electric potential in a dearsenic reaction tank, and Cu / As ratio in embodiment of the wet processing method of the zinc leaching residue by this invention. 6 is a graph showing the relationship between the potential in the dearsenic reaction tank and the quality of indium in the dearsenic residue in the embodiment of the wet processing method for zinc leaching residue according to the present invention. 4 is a graph showing the relationship between the Cu / As ratio of the dearsenic reaction tank and the quality of indium in the dearsenic residue in the embodiment of the wet processing method for zinc leaching residue according to the present invention.

Claims (14)

The leaching process in which zinc leaching residue, which was removed as a solid content by leaching calcination ore by wet zinc smelting and solid-separated, was leached with acid and solid-liquid separated, and the leachate obtained in this leaching process A first stage neutralization step for neutralization and solid-liquid separation, a arsenic removal step for removing the neutralized solution obtained in the first stage neutralization step for solid-liquid separation, and a arsenic removal step A second-stage neutralization step of neutralizing the obtained liquid and separating it into a solid and a liquid; and a deironing step of removing iron from the neutralized solution obtained in the second-stage neutralization step and separating it into a solid and liquid In the wet leaching method for zinc leaching residue, when the neutralized solution obtained in the first stage neutralization step is de-arsenized, zinc powder and a copper ion source material are added to the neutralized solution. , Wet processing method of zinc leaching residue. The wet processing method for a zinc leaching residue according to claim 1, wherein the copper ion source material is copper sulfate. The amount of the copper ion source material added is based on the ratio of Cu concentration (Cu / As ratio) to the concentration of As in the reaction tank for removing the neutralized solution obtained in the first stage neutralization step. The method for wet treatment of zinc leaching residue according to claim 1 or 2, characterized in that it is determined. The wet processing method of a zinc leaching residue according to claim 3, wherein the addition amount of the copper ion source material is determined so that the Cu / As ratio is 1.5 or more. The amount of the copper ion source material added is determined on the basis of a potential in a reaction tank for de-arsenizing the neutralized solution obtained in the first stage neutralization step. The wet processing method of the zinc leaching residue described in 1. 6. The method for wet treatment of zinc leaching residue according to claim 5, wherein the addition amount of the copper ion source material is determined so that the potential becomes -320 mV or more. The zinc according to any one of claims 1 to 6, wherein at least one valuable metal selected from the group consisting of gold, silver, copper, iron and lead is separated and recovered from the zinc leaching residue. Wet treatment method for leach residue. In the leaching step, electrolytic tail liquor in wet zinc smelting is added to the zinc leaching residue to form a pulp, and then leached in a reducing atmosphere to separate into solid and liquid, solids containing lead and silver as main components, and others The method for wet-treating a zinc leaching residue according to any one of claims 1 to 7, wherein the wet leaching residue is a step of separating into a leaching solution containing the components. In the first stage neutralization step, calcium carbonate is added to the leachate obtained in the leaching step, the free sulfuric acid in the leachate is neutralized and solid-liquid separated, and the solid content mainly composed of gypsum, and others The method for wet treatment of a zinc leaching residue according to any one of claims 1 to 8, wherein the wet leaching residue is a step of separating the leaching residue into a liquid containing the above components. The dearsenation step is performed by solid-liquid separation by adding zinc powder and a copper ion source material to the neutralized solution obtained in the first stage neutralization step, and a solid content mainly containing copper and arsenic as copper arsenide; The method for wet-treating a zinc leaching residue according to any one of claims 1 to 9, wherein the method is a step of separating into a liquid containing other components. In the second-stage neutralization step, the solid after separating copper arsenide in the dearsenation step is subjected to solid-liquid separation by adding pH to calcium carbonate, solid content mainly composed of aluminum, and other components The method for wet treatment of a zinc leaching residue according to any one of claims 1 to 10, wherein the wet leaching residue is a step of separating the leaching residue. The iron removal step is a step of separating the liquid after separating the aluminum in the second stage neutralization step, hydrolyzing the iron while oxidizing it in the hematite generation temperature region, and then solid-separating the solid content containing iron as hematite; The method for wet treatment of a zinc leaching residue according to any one of claims 1 to 11, wherein the method is a step of separating into a liquid containing zinc. Zinc powder is added to the liquid obtained in the second stage neutralization step and solid-liquid separated between the second stage neutralization step and the iron removal step, and arsenic, cadmium and lead are contained as main components. 13. The method for wet treatment of zinc leaching residue according to any one of claims 1 to 12, further comprising a second-stage de-arsenation step for separating a solid and a liquid containing other components. The amount of copper in the leaching solution obtained in the leaching step is 3 mol or more with respect to 1 mol of arsenic, and the leaching solution is reacted with arsenic in the dearsenic step to form copper arsenide. Item 14. A wet processing method for a zinc leaching residue according to any one of Items 1 to 13.

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